There is no one 'best' guide for Sandy Point that I have found. Personally, I use a range of sources of info:
The predictions from 'Windfinder' are quite reliable most of the time, at least to a couple of days out.
'Windguru' tends to under estimate from West to South West directions but Mathews modification is usually pretty close.
The new 'Predictwind' service is excellent as well.
Other computer models may be found on Weatherzone that are also very good indicators.
The things to remember about computer models is that the closer you are to the prediction time, the better they are. Also, the better different models agree, the better they are probably predicting for that time and place.
For current conditions I look at a combination of the reports from Wilsons Prom, Yarram and South Channel in combination with looking at the isobar maps to get an idea of what Sandy is like. It is usually not the same as any of those stations but experience can help you see a pattern and make a judgment.
eg. For stable summer highs the South Channel readings are often pretty close to Sandy Point. The Prom readings are about 30% higher than Sandy on West to South Westerlies but pretty close on summer Easterlies.
Yarram is the next closest and being on the coastal plain it is a very good indicator in easterlies as well but usually a bit under the winds at Sandy and well under on West to SW
Andrew Watkins website also has some excellent links and resources for current readings and forecasts as well.
Hope this helps.